69 BB Timing
Thread Starter
Racer
Joined: Apr 1999
Posts: 418
Likes: 2
From: Fort Mohave Az.
69 BB Timing
I am having a heating battle. I have addressed all of the most common solutions, ie. radiator, front dam, fan stuff. I am quite sure its in my time. I put in a Pertronics and battled with the timing. I shopped the job out and found out that my timing light (10 years old at least) was bad. I am getting a new light this weekend, and want set it up again. What is the best settings for BB?
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: 69 BB Timing (69L68)
I have been through all of this. You MUST run at least 93 octane. Amoco seems to be the best. Set initial timing at 6-8 degrees BTDC. install a distributor recurve kit. Use the stock GM weights. Use the bushing that give 28 degrees total and the springs that allow it to be all in at 3000rpm. Do not use a vacuum advance. This will give you a very good drivable curve that will not ping except under severe load.
Melting Slicks
Joined: Mar 1999
Posts: 2,845
Likes: 2
From: Apex NC
Re: 69 BB Timing (silvervetteman)
I agree with everything that silvervetteman has said, EXCEPT for the part about not using a vacuum advance can. If you're having overheating problems at idle, it may be due to no vacuum advance. I'm no guru on this, but there have been tons of posts over on the technical discussion board at http://www.ncrs.org surrounding overheating on big blocks at idle. Lots of good information there on why vacuum advance is a "Good Thing" (tm).
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: 69 BB Timing (sb69coupe)
I agree with everything that silvervetteman has said, EXCEPT for the part about not using a vacuum advance can. If you're having overheating problems at idle, it may be due to no vacuum advance. I'm no guru on this, but there have been tons of posts over on the technical discussion board at http://www.ncrs.org surrounding overheating on big blocks at idle. Lots of good information there on why vacuum advance is a "Good Thing" (tm).
Melting Slicks
Joined: Oct 2000
Posts: 3,023
Likes: 2
From: TEXASTEXASTEXASTEXAS TEXASTEXASTEXASTEXAS
St. Jude Contributor
Re: 69 BB Timing (Fevre)
I run no vacuum advance and get no overheating, not even here in central hell (I mean, central Texas :D ).
I run 93octane Chevron (no Amoco in my town). To get rid of pinging, I've retarded total advance to about 24degrees and my initial advance is at about 1degree. I've changed the jets and metering rods out to a set that Lars suggested and that helped a LOT. Now I only get pinging at very hard acceleration. I don't think I'll get rid of that without better gas, though I'm going to try running some tranny fluid through the carb to burn out carbon deposits & see if that helps.
JB
I run 93octane Chevron (no Amoco in my town). To get rid of pinging, I've retarded total advance to about 24degrees and my initial advance is at about 1degree. I've changed the jets and metering rods out to a set that Lars suggested and that helped a LOT. Now I only get pinging at very hard acceleration. I don't think I'll get rid of that without better gas, though I'm going to try running some tranny fluid through the carb to burn out carbon deposits & see if that helps.
JB
Thread Starter
Racer
Joined: Apr 1999
Posts: 418
Likes: 2
From: Fort Mohave Az.
Re: 69 BB Timing (69L68)
Thanks for the responce guys. You REALLY got me thinking. I can actually do a cruising around town with no problem at all. Matbe even for an hour or so. My biggest problem occurs when I want to for a run on the freeway. If I run about 70 mph for even 45 min. it seems like it gets pissed at me. Could it possibly my distributor sticking?
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: 69 BB Timing (69L68)
Retarded timing will cause heating problems for sure. Make sure the inner shaft in the ditributor is free. Check for worn wieght bushings and make sure the the limit bushing I spoke of earlier is still there. The fatory one is plastic and sometimes falls apart an that will cause way too much advance which can also cause overheating.. There is a sweet spot temperature wise for these big blocks. They do not like to run warmer than 200 deg. Mine only gets to 200 when I sit in traffic with the A/C on and the outside temp is in the mid 90's
